Method of treating electrolytic slimes for the recovery of metals therefrom.



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Specification oi l'iett'era Patent.

Patented Jan. 45," 1909.

Applica ion meuwpvembu 26, 1906. -8erla1=No.=845, 082.

"Tana where it may concern:

'Beit known that I, ALEXANDERJ. McNAB,

--a citizen ofCanada, residing at Trail, British --s'ult ing from the electrolytic refining of base -bul1ion,.for example leadbullion. An eco nominal and effective process or method for this purpose; has long-:been. sought, and to provide such-a method or process is the objectof my present invention. The particular slimes which I have in mind are the so-called silver 'slimes :resulting from the electrolytic refining of lead-bullion, but the process is, -in general, applicable to advantage inithe case of other similarby-products, as for example the slimes which result inlarge-quantities from the electrolytic refining of blister copper.

In practicing my process the slime, for example that resulting from lead refining by the Betts electrolytic recess, is first treated with a sulfid, polysulfid jor hydrosulfid of' an'alkali,

as sodium, potassium, or ammonium. 1 prefer sodium polysulfid for the purpose, as this compound is'cheap, gives off-no ofl'ensive' odorduring subsequent electrolysis, and dissolves-the antimony and arsenic ofthe slime more readily than does the sulfid,

v'lhe treatment with polysulfid just 'mentioned dissolves what antimony,-arsenic, tellurium and selenium maybe present in the slime in the metallic form or as compounds, co'nvertingthe same, in'general, into sulfids. Thus, the antimony,p resent both inthe metallic form and in compounds, chiefly the latter asantimonidsof silver, copper and lead, is converted mostly into Na bbs though other similar compounds, as Na SbS 'maybe formed. Similarly, the arsenic combines \gitlfi the re-agent to Na Ass or Na,,AsS or The silver, lead, bismuth, copper, and gold present in the slime are left undissolved by the above treatment. The solution, containing the other metals, is separated from the residue in any suitable way, as by filtration, and subjedted to electrolysis, lpreferably with carbon or lead anodes and wit cathodes of iron, copper, lead or other suitable metal.

In the electrolysis antimony is deposited on the cathode, whilegihe sulfid solution is' regenerated. The aiitimony deposited on the cathode is stripped oil as desired, and melted and cast into ingots in the ordinary way. When thesolut-ion or bath becomes too' feul for further electrolysis, that is, when the bath has accumulated too much arsenic from re lenishment of the bath with fresh so ution, so that the'bath'oannot be electroof lead, bismuth, co par, "and gold.

residueis now roaste ,to convert the silver sulfid largely into sulfate, at the "time converting most if not all of z'tlre ether vmetallic sulfids 4 into sulfates. The roasted .residuei's then treated withwater or dilute sulfuric acid, pfreferably the 'latterydissolving the copper su ate, mostofthesilversulfate and to some extent the bismuth sulfate.

This solution is :separate-dlrom the-residue, which consists 'mostly of metallic gold a'r'rd silver, lead sulfate, and basic bismuth -sul'- fate. .The silver'and bismuth inthe above solution is-then precipitated by-copperbr other suitablezmetal-or compound, 'and"the preci itated metals are melted down in a rever eratory' furnace, during "which the bismuth is oxidized oil and recovered oxid, which can be 'further treated in any well understood Way. to convert it '-in'to.metallic bismuth, bismuth onychlorid,-'or-other desired form. The filtrate resulting from the precipitation of silver and bismuth may be concentrated and allowed to stand to crystallize the cop er'sulfate resulting from the treatment oft e original solution with copper, and to recover the tree sulfuric acid, which is to be used over again.

The residue of metallic gold and silver, lead sulfate and basic bismuth sulfate, is

laser AVAILABLE coi r Q charged into a reverberatory furnace, the lead and bismuth oxidized off. and the bismuth recovered-by any of the well known chemical processes.- The mixture of gold and silver resulting from this fusion may be parted by any suitable and convenient chemical or electrochemical process, to re cover the silver and gold.

What Iclaim is:

1. The herein-described method of treating electrolytic slimes for the recovery of metals therefrom, which consists in treating the slime with an alkali-sulfid, separating from the residue the solution thus formed, separating a metal from the solution by electrolysis, and roasting the residue and recov ering metals therefrom, as set forth.

2., The herein-described method of treating electrolytic slimes for the recovery of metals therefrom, which consists in treating the slime with. an alkali-sulfid, whereby antimony and arsenic in the slime are converted into soluble sulfids; depositing antimony on a cathode by electrolysis; and se arating arsenic from the electrolyzed bath y crystallization; as set forth. V

3. The herein-described method of treating electrolytic slimes for' the recovery of metals therefrom, which consists in treating the slime with an alkali-sulfid, whereby antimony and arsenic in the slime are converted into soluble sulfids: separating the solution from theresidue and separating antimony from the solution by electrolysis; and recovering metals from the said residue by roasting and subse uent treatment, as set forth.

1 4. The herein-described method of treating electrolytic slimes containing silver for the recovery of metals therefrom, which consists in converting one or more of the metals of the slime into soluble sulfids; separating the soluble suliids, in solution, from the residue; roasting the residue and converting more or less silver therein into sulfate, in solution; and precipitating metallic silver from the said solution by a suitable reagent; as set forth.

5. The herein-described method of treating electrolytic slimes for the recovery of metals therefrom, which consists in converting one or more metals thereof into insoluble sulfids and one or more into soluble sulfirls; separating the soluble sulfids, in solution, from the insoluble sulfids, or residue; subjecting the sulfid solution to electrolysis to recover a metal therefrom; and roasting the said residue and recovering metals therefrom; as set forth.

6. The herein described method of treating electrolytic slimes containing silver for the recovery of metals therefrom, which consists in treating the slime with an alkalisulfid; separating from the residue the solution thus formed; electrolyzing the solution to remove antimony therefrom; crystallizing arsenic out of the electrolyzed bath; roasting the residue resulting from the treatment with alkali-sulfid; treating the roasted residue with a reagent to dissolve silver sulfate therefrom, and separating the same from the residue; and precipitating the silver from the sulfate solution; as set forth.

7 The herein-described method of treating electrolytic slimes containing silver for the recovery of metals therefrom, which consists-in converting more or less of the metals of the slime into soluble and insoluble com pounds; separating the dissolved compounds from the residue; roasting the residue and dissolvin therefrom silver sulfate; precipitating the silver from the sulfate solution y a suitable reagent; charging into a reverberatory furnace the residue resulting from the separation of silver sulfate,- to oxidize off lead and bismuth; and parting the metals resultin from the fusion in the furnace; as set fort 8. The herein-described method of treating electrolytic slimes for the recovery of antimony, arsenic, bismuth, gold and silver therefrom, which consists in converting antimony and arsenic into soluble sulfids and separating the same, in solution, from the ot 1er substances; roasting the other substances or residue, containing bismuth, gold and silver; and convertin more or less of the silver into soluble su ate and bismuth into soluble and insoluble sulfates; separating the sulfate solution and precipitating the silver and bismuth in metallic form;charging the precipitated silver and bismuth into a reverberatory furnace, oxidizing off the bismuth, recovering the same and the silver; charging into a reverberatory furnace the residue resulting from the separation of bismuth and silver sulfates, containing metallic old and silver and insoluble bismuth sulfate; oxidizing oil the bismuth and recoverin the oxid; partin the mixture of metallic gold and silver resu ting from the fusion in the furnace; and recovering the antimony and arsenic from the solution of their sulfids; as set forth.

ALEXANDER- J. MoNAB.

Witnesses A. BRUCE Rrrcmn, M. H. SULLIVAN. 

